Reset generators are used to apply a reset signal to processors and other circuits. Such a signal may be provided shortly after a circuit has powered up so as to ensure that it is in a known state. They may also be used to supply a reset signal in the event of power supply “brown out” or if a processor gets “hung” or otherwise stalled such that it is probable that its operation has become compromised.
It is well recognised that an important aspect of the “reset” function is to avoid giving false reset signals to the processor. As a result the reset generator is generally designed to be robust in the presence of noisy supplies.
A particularly difficult case is the state or evolution of the reset signal itself on initial power up of the reset circuit, especially when this coincides with device power up.